Add protection against concurrent Readers

[oslook]

During my use of the library(server and client both v1.8.7), the server occasionally receives the following prompt,

failed to get reader: received header with unexpected rsv bits set: false:true:true

which seems to be related to this part of the code.

write.go L300:

	c.writeHeader.rsv1 = false
	if flate && (opcode == opText || opcode == opBinary) {
		c.writeHeader.rsv1 = true
	}

Could you please confirm if it is necessary to add the following code here?

	c.writeHeader.rsv1 = false
	c.writeHeader.rsv2 = false
	c.writeHeader.rsv3 = false

[vendion]

I'm getting something slightly similar using the same version: failed to get reader: received header with unexpected rsv bits set: true:true:true

[soypat]

Me too- I've checked with wireshark and the websocket frame is OK, it's just being parsed wrong on nhooyr/websocket's side.

[nhooyr]

That's quite concerning that all three of you guys are seeing that... I'd suggest disabling compression though it'll be disabled by default in the next release.

I'll go through the code again to see if I can find the bug. The autobahn compression tests pass fine under the race detector so I'm surprised to see a bug like this.

[nhooyr]

@soypat If possible, can you share the frames you checked with wireshark? Maybe I can replay them with the library and thus reproduce. That would help immensely in debugging.

[nhooyr]

There's been enough changes for v1.8.8 that whatever this was is likely fixed. Compression in particular is disabled by default now and I recommend keeping it that way. Let me know if you see it again once v1.8.8 is released.

[nhooyr]

Nvm I was able to reproduce, see 249edb2